Measurements: Chest width relation with jacket & coat real size

If your chest measures 40" you likely wear a size 40 (suit) jacket. If you measure the jacket, it is 4” larger than the actual chest measurement, so the real size would be 44".

I was wondering how many inches are added to each kind of garment. 4" seems to be the average for a suit jacket, so you can breath and wear a shirt underneath. What about overcoats, is there an average measure relation too, so you can wear a jacket or cardigan and breath? And sport leather jackets?

I got the 4" from here. Is it wrong then? -> http://www.askandyaboutclothes.com/t...easurement.htm

What about coats? I have an italian leather jacket that is size 42, when I use to wear 38. But when I measured the jacket it was 42", so the label size was the real one. Sometimes you cannot trust the label because it can indicate that the garment is made for people with that body size or that the real jacket size is that.

So +2" for suit jackets and +4" for coats and leather jackets then?

Where is the original thread?